In the field of electrophotography, with the progress of electrophotographic systems, it has been demanded to develop toners for electrophotography which are adaptable for high image quality and high copying or printing speed. To meet the requirement of a high image quality of toners, there are known processes for producing toners having a narrow particle size distribution and a small particle size by an aggregating and coalescing method (emulsification/aggregation method or aggregation/unifying method) in which fine resin particles, etc., are aggregated and coalesced together in an aqueous medium to obtain the toners. Furthermore, in order to improve basic properties of the toners such as low-temperature fusing properties and storage stability thereof, there have been made studies on development of resins having a specific structure for use in the toners.
For example, JP 2014-126862A discloses a process for producing a toner for development of electrostatic images which exhibits both good low-temperature fusing properties and good heat resistance/storage properties, and are free from occurrence of toner cloud and excellent in charging stability and charging rise-up properties. In the process described in JP 2014-126862A, after mixing resin particles containing a crystalline polyester and releasing agent particles containing a releasing agent with each other, an aggregating agent is added dropwise to the resulting mixed particles at a predetermined temperature, and the obtained mixture is maintained at a predetermined temperature to obtain aggregated particles, and then resin particles formed of a graft polymer containing a main chain segment constituted of a polyester resin and a side chain segment constituted of an addition-polymerized resin are added to the aggregated particles to aggregate and coalesce the aggregated particles with the resin particles, thereby obtaining core/shell particles.
In addition, JP 2007-93808A discloses a toner for electrophotography which contains a polyester obtained by polycondensing a raw material monomer including a monovalent aliphatic compound that has a number-average molecular weight of 400 to 1000 and is at least one compound selected from the group consisting of a monovalent aliphatic carboxylic acid compound and a monovalent aliphatic alcohol, as a resin binder, and which is excellent in dispersibility of a releasing agent therein and has good anti-offset properties.
Furthermore, JP 2014-232168A discloses a toner for development of electrostatic images including a resin binder for toners which includes a polyester resin portion and a vinyl-based resin portion containing constitutional units derived from styrene and (meth)acrylic acid, and further includes a specific amount of a structural moiety derived from a hydroxy group-containing hydrocarbon wax having a melting point of 60 to 110° C., and can exhibit both good low-temperature fusing properties and good long-term storage stability under high-temperature and high-humidity conditions.